Hand block for abrasives, etc.



Sept. 14 1926.

W. L. M KNIGHT HAND BLOCK FOR ABRASIVES, ETC

Filed June 5, 1923 I 2 Sheets-Sheet 1 RN 9. E'

w. L. MCKNIGHT HAND BLOCK FOR ABRASIVES, ETC

Sept. 14 1926.

Filed June 5. 1925 2 Sheets-Sheet 2 Patented Sept. 14, 1926.

UNITED STATES PATENT OFFICE WILLIAM LESTER MOKNIGHT, OF ST, PAUL, MINNESOTA, ASSIGNOR T MINNESOTA MINING AND MANUFACTURING COMPANY, OF ST. PAUL, MINNESOTA, A CORPORA- TION OF MINNESOTA.

HAND BLOCK FOR ABnAs'IvEs, ETC.

Application filed June 5,

This invention relates broadly to support ing and sustaining means, more particularly to an improved hand block for supporting and sustaining a sheet of. abrasive material or the like, and especially one characterized by the feature of retaining such sheet by the tension of the block and pressure of the hand grasping the block and for tensioning the sheet relatively to the block when in use. r

This invention is further characterized by the provision of a hand block having a shape which permits easy grasping by the hand, and which facilitates reversal of the I5 block when desired.

The foregoing and such other objects and advantages as may appear or-be pointed out as this description proceeds, are attained in a structural embodiment illustrated in the accompanying drawing, in which Figure 1 is a perspective view of the device of this invention;

Figure 2 is a top plan view of the same; Figure 3 is a fragmentary side elevational 5 view;

Figure 4 is a transverse sectional view taken on the line 4 -4 of Figure 3, looking in the direction indicated by the arrows;

Figure 5 is a view similar to Figure 1 of a modified or alternate application of the invention;

Figure 6 is a fragmentary side elevational view of the same, illustrating the block appligd to use in working a curved surface,

Figure 7 is a transverse sectional view taken on the line 7-7 of Figure 6.

Referring more particularly to the drawings, and first to Figures 1 to l, inclusive, I provide a ,block 5 offlexible material, such as rubber or the like, having an upper curved surface 6 and a lower straight surface 7, the block being substantially rectangular in general form and having recesses 8-8 in the side walls 99 thereof to afiord means whereby the operator may grasp the block.

The block is provided with slots 10 and 11, saidv slots extending inwardly, and divergently with respect to the top wall 6,

i from the end walls 12 and 13 to approximately the medial portion of the block. The inner ends of the slots 10 and 11, of course, will be placed a suflicient' distance 1923. Serial No. 643,489.

apart so as not to weaken the medial portion of the block, appreciably.

The formation of the slots 10 and 11 provides flexible tongues 14 and 15 and said slots are located in planes angularly related and intermediate of the top 6 and lower surface 7 of the block. While the slots are conveniently arranged in planes which are angularly related to the surface 7, this is not absolutely essential, but, for a purpose ,which will presently appear, is to be preferred. I

The block in the present use to which it is put receives a flexible sheet 16 of abrasive material, the major portion of the sheet lying against the surface 7 and the ends 17 and 18 of said sheet being extended into the slots 10 and 11 between the block and the tongues 14 and 15.

In order to firmly hold the abrasive sheet in position and also for the purpose of tensioning said sheet when in use I provide a series of fastening devices in each of the slots. These fastening devices conveniently take the form of prongs 19 and 20, embedded in the rubber or other flexible material from which the block is made, and said prongs or pins lie in planes which are conveniently radii of the curved surface 6, and, therefore, substantially perpendicular to the slots. The prongs project from the block into coinplemental recesses 21 and 22 formed in the tongues 1 1 and 15, and in engaging said recesses the prongs necessarily puncture the abrasive sheet at a plurality of points, as will be best seen in Figure 1, and thereby serve to firmly anchor the ends of the abrasive sheet in the slots 10 and 11. y

In the use of the device as illustrated in Figures 1 to 4, the abrasive sheet 16-, being applied to the surface 7 is, with the block, manipulated by grasping the upper portion of the block, the recesses 88 affording means for grasping the block, the palm of the operators hand resting upon the curved surface 6. This curved surface coilforms generally to the shape of the hand when grasping the block and thereby more readily fits the operators hand and prevents undue strain upon and tiring of the muscles of the hand. It will be understood, of course, that while the curved surface as shown is curved longitudinally of the block, this surface may also be curved transversely so that the upper part of the block in this instance may take a curved shape. However, the block is shown with the single curvatureso as to facilitate its use as hereinafter described with respect to Figures 5 to 8, inclusive. The grip on the block and pressure applied when in use causes the tongues 14 and 15 to engage the abrasive sheet, and, together with the pins 19 and 20, the tongues prevent movement of the sheet relative to the block, and thus permit a more efficient operation.

Referring now to Figures be observed that in addition to the use of 'the book as previously described, the device curved surface 6.

The shape of the surface 6, and the arrangement of the slots 10 and 11, and fastening pins 19 and 20, afl'ord means whereby when grasped by the hand of the operator and when pressure is applied to the block a gripping action is set up between the tongues 14 and 15 and the adjacent surfaces of the block and as the block and tongues are flexed in operation the abrasive sheet will be subjected to tension, this being due to the fact that a flexing or curving of" the block, by applying pressure to its medial portion, in effect lengthens the surface 6 and as a consequence stretches or makes taut the abrasive sheet. This is particularly advantageous for the reason that it prevents movement of the sheet relative to the block .and, of course, it follows' that a more effiture of the block insures that the operator can maintain a firm grip thereon.

In order to insert a sheet of abrasive material into the block inveither of its uses described, one or-the other of the tongues 5 to 7, it will 14 or 15 is bent outwardly as shown in dotted lines in Figure 5, and one end of the abrasive sheet is then inserted, the tongue released and slight pressure applied so as to puncture the sheet with the prongs or pins 19 or 20, as the case may be. The sheet 1s then brought over either the surface 6 or 7 and while maintaining said sheet under tension the other tongue at the opposite end of the block is flexed outwardly, the adjacent end of the sheet inserted and the tongue then released and the pins serve to hold this end of the sheet against accidental displacement. The recesses 2122 are preferably countersunk as at 21, 22 to guide the pins 19 and 20 thereinto.

lVhile in the form of the invention shown the block is preferably made of a single piece of material which is flexible, such as medium soft rubber, it will be obvious that if desired the upper part of the block may be made of hard rubberand the lower part of,relatively soft rubber, or vice versa. The

nature of the device also readily permits of its embodiment in apparatus for operating the abrasive block, and, therefore, the invention finds a wide field of utility for purposes other than and similar to that described.

l-l'aving thus described my invention and illustrated its use, what I claim as new and desire to secure by Letters Patent is 1-- 1. A polishing implement comprising a block of resilient materialhaving oppositely located slits, pointed members carried by the block and extending into said slits, and a strip of material held upon and in contact with said block by said pointed members engaging edges of said strip inserted in said slits.

2. A polishing implement comprising a block of resilient material having oppositely located slits, pointed members carried by the block and extending into said slits, and a strip of material held upon and in contact with said block by said pointed members passingithrough edges of said strip inserted in said slits.

In testimony whereof I have hereunto signed my name.

WILLIAM LESTER MOKNIGHT. 

